Typically, the axle hub on a vehicle is exposed to view from the exterior of the vehicle. The appearance of this hub in some instances is not desirable due to its utilitarian design. The use of decorative hub covers recognizes the desire for an improved appearance of this area of the vehicle, typically regarded as the tire and wheel assembly. It is well known to cover the hub or exposed wheel of an automobile tire and wheel assembly with a decorative cover—or hub cap—to both improve the aesthetic impression of the vehicle and to reduce the amount of dirt and grime that comes into contact with the exposed lug nuts that hold the wheel to the axle hub.
The decorative hub covers must be removed from the wheel periodically in order to service the tire, wheel, brakes, hub, or axle. For example, in some assemblies where the axle hub has a grease fitting installed, the decorative hub cover must be removed to apply grease to the wheel bearing assembly as a matter of routine maintenance. In other vehicles, it is recommended that the torque value of the lug nuts be checked periodically to ensure proper, safe wheel mounting. Such periodic maintenance generally requires the hub cover to be removed from the wheel to perform the maintenance and then remounted to the wheel afterward.
Many typical known hub covers include a frictionally engaged, resilient locking system whereby the cover is snap-fitted to the hub by pressing the cover axially onto the wheel. One or more resilient engagement surfaces then snap into a groove or recess in the wheel to releasably lock the cover to the wheel. Most of these designs require the use of tools to some extent to either install or remove the decorative hub cover. Some decorative hub covers even take into account the needed tool by providing a slot in the cover so that the tool can be inserted into the slot to pry the cover from the tire and wheel assembly. Such a slot prevents the tool from damaging the finished surface of the decorative hub cover, which is often highly polished. This design, however, is problematic because the finished surface of the wheel itself or its decorative trim is usually damaged by the prying necessary to remove the hub cover.
Other such decorative hub cover designs leave it up to the individual to determine the best method of mounting and removal in order to minimize the damage to the surfaces of both the hub cover and the wheel. This does nothing to minimize the damage caused by applying tools to the surfaces of the decorative hub cover or the tire and wheel assembly.
Another known decorative hub cover design is described in U.S. Pat. No. 4,217,003 and obviates the need for using tools to attach and release the cover to the wheel by rotatingly engaging a plurality of open faced, single walled retention members about the wheel axis into engagement with the lug nuts. The plurality of retention members act together to maintain the cover on the wheel by collectively defining an intermittent ridge or surface about the exterior of all the lug nuts that fits into the radially distal portion of each of the grooves defined between the lug nuts and the wheel. A resilient camming surface in each of the retention members prevents the cover from unwanted rotational disengagement with lug nuts. This cover attachment design thereby allows the cover to be attached and released from the wheel by simply rotating the plurality of retention members about the lug nuts about the wheel's axis without the need for additional tools. A problem with this design, however, is that the retention members must act collectively to lock the cover to the lug nuts. If some of the retention members are broken, the remaining retention members may not be able to maintain the cover on the lug nuts.
Therefore, it would be desirable to have a cover for a wheel or hub that may be attached and released to the lug nuts without requiring the use of additional tools. It would also be desirable to have a cover with an attachment system that will maintain the cover on the wheel even if some portions of the attachment system become inoperable.